A partial or median sternotomy is a procedure by which a saw or other appropriate cutting instrument is used to make a midline, longitudinal incision along a portion or the entire axial length of the patient's sternum, allowing two opposing sternal halves to be separated laterally. A large opening into the thoracic cavity is thus created, through which a surgeon may directly visualize and operate upon the heart and other thoracic organs or tissues. Following such a procedure, the two severed sternal halves must be reapproximated.
Traditionally, sternal halves have been reapproximated with stainless steel wires wrapped around or through the sternal halves so as to exert medial compression thereon and twisted together to approximate the sternum. Other methods of sternum repair include the use of band or strap assemblies which typically include a locking mechanism, which secures a strap in a closed looped configuration about the sternum positions. While utilization of steel wires and strap assemblies have been widely accepted for sternum repair, these devices present a number of disadvantages. Steel wires can and do break, and provide insufficient(non-uniform) clamping force resulting in sternal nonunion. Steel wires are difficult to maneuver and place around the sternum. The cut ends of the steel wires are also sharp and can pierce through the surgeon's gloves or fingers. In addition, the small diameter of the steel wires can cause the wires to migrate into or through the tissue surrounding the sternum region or into the sternal bone itself over time and result in sternal disintegration into small segments. This can lead to significant patient pain and discomfort in addition to slowing the postoperative recovery and increasing the risk of sternal infection. Moreover, the strap mechanisms of band assemblies are often relatively structurally complex and are difficult to precisely apply about the sternum. There are also healing problems associated with the use of steel wires and band assemblies due to improper forces exerted by these devices which can cause unwanted bone movements leading to raking and rubbing of surrounding tissue or bone.
Several other techniques of sternal reapproximation have been proposed both for primary closure following a median sternotomy and for reclosure following post-operative emergency surgical procedures. One such sternal fixation device is described in U.S. Pat. No. 6,051,007 entitled External Closure Device and Instruments Therefor, the entire contents of which are incorporated by reference.
The sternum closure device of U.S. Pat. No. 6,051,007 however is clearly absent the benefits and teachings of the instant invention. Most particularly foot portions (20, 40) of the '007 device are limited to two points of contact on the posterior section of a patient's sternum and consequently lack the stability and positioning enhancement features of the instant invention. Quite distinguishable, from the '007 patent and other devices practiced in the contemporary art is the present invention's novel structure which advances the art by allowing and encouraging divided sternal plates to be tilted upward to maximize healing surfaces in apposition to each other, thus avoiding downward plate deflection and substandard healing. Also distinguishable from devices of the contemporary art, the instant invention spans the width of at least two interspaces, thus eliminating the need for more than one device for tight/secured closure over the same sternal area. The four securing leg and foot structures of the instant invention improve pulmonary mechanics by assisting in the alignment of ribs across the sternotomy allowing for simultaneous right and left rib elevation symmetrically across the sternum and chest. The projection member structures of the instant invention leverage the tight connections provided by fascia and muscle, strengthens pulmonary compliance and allows for distribution of energy and positioning strength to be spread evenly throughout the sternum. Most distinguishable from the contemporary art, the instant invention enables fragmented segments of the sternum to be held in place for healing, as opposed to single plate structures of the contemporary art which concentrate (as opposed to distribute) energy occasionally to a crushing central point thereby allowing laterally displaced fragments to further displace.
The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages, and embodiments of the invention will be apparent to those skilled in the art from the following description, accompanying drawings and claims.